#region License
// Copyright 2008-2009 Jeremy Skinner (http://www.jeremyskinner.co.uk)
// 
// Licensed under the Apache License, Version 2.0 (the "License"); 
// you may not use this file except in compliance with the License. 
// You may obtain a copy of the License at 
// 
// http://www.apache.org/licenses/LICENSE-2.0 
// 
// Unless required by applicable law or agreed to in writing, software 
// distributed under the License is distributed on an "AS IS" BASIS, 
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
// See the License for the specific language governing permissions and 
// limitations under the License.
// 
// The latest version of this file can be found at http://www.codeplex.com/FluentValidation
#endregion

namespace FluentValidation.Validators
{
    using System;
    using Internal;
    using Results;

    public abstract class AbstractComparisonValidator<T, TProperty> : IPropertyValidator<T, TProperty>, IComparisonValidator where TProperty : IComparable<TProperty>
    {
        readonly Func<T, TProperty> _valueToCompareFunc;

        protected AbstractComparisonValidator(Func<T, TProperty> valueToCompareFunc)
        {
            valueToCompareFunc.Guard("The value to compare cannot be null.");
            _valueToCompareFunc = valueToCompareFunc;
        }

        #region IComparisonValidator Members
        public abstract Comparison Comparison { get; }
        //TODO: check this Setter not used...
        public object ValueToCompare { get; private set; }
        #endregion

        #region IPropertyValidator<T,TProperty> Members
        public PropertyValidatorResult Validate(PropertyValidatorContext<T, TProperty> context)
        {
            TProperty value = _valueToCompareFunc(context.Instance);

            if (context.PropertyValue == null || !IsValid(context.PropertyValue, value))
            {
                MessageFormatter formatter = new MessageFormatter()
                    .AppendProperyName(context.PropertyDescription)
                    .AppendArgument("ComparisonValue", value);

                string error = context.GetFormattedErrorMessage(GetType(), formatter);
                return PropertyValidatorResult.Failure(error);
            }

            return PropertyValidatorResult.Success();
        }
        #endregion

        public abstract bool IsValid(TProperty value, TProperty valueToCompare);
    }

    public interface IComparisonValidator : IPropertyValidator
    {
        Comparison Comparison { get; }
        object ValueToCompare { get; }
    }

    public enum Comparison
    {
        Equal,
        NotEqual,
        LessThan,
        GreaterThan,
        GreaterThanOrEqual,
        LessThanOrEqual
    }
}